How to find cylinder dimensions from volume and aspect ratio?

Okay, so basically what I'm trying to figure out is how to find the dimensions (length and diameter) of a cylinder when I know the volume and the ratio of length to diameter (for instance, a cylinder x times longer than it is wide). Unfortunately, I haven't been able to figure out how to do so on my own and google hasn't exactly been helpful. I'm quite stumped, so I would greatly appreciate any help.